lactose intolerance?

For a few weeks I was eating a mainly vegan diet (not really deliberately), except I was eating a strawberry yogurt most days. I started to notice I was feeling nauseous after eating the yogurts so I cut them out. 

Since over 2 weeks ago I have started feeling a lot of discomfort in my stomach. It began with me feeling nauseous for a couple of days, and then one day I woke up with really bad stomach cramps which lasted for a few hours and then came back whenever I eat throughout the day. Since then the stomach cramps have continued most days after I eat along with flatulence, bloating, & some nausea. I thought I'd probably had a stomach virus or something so didn't pay much attention..

But now it's been going on for over 2 weeks, and I've realized that the onset of these symptoms may coincide with reintroducing dairy products back into my diet. I've started experimenting a bit and found that I get stomach cramps and wind and sometimes nausea after eating products that contain milk. If I stick to vegan foods I seem to be fine. I've also noticed that if I eat dairy products in the evening, I get cramp throughout the night and wake up with occasional stomach cramps, feeling bloated, 'sick', full and nauseous. 

Does anyone know if this could be lactose intolerance? I'm puzzled because I've never been sensitive to dairy products before, although I never really eat much of them. I swapped to soya milk about 2 years ago and haven't drank cows milk since. I also usually have soya yogurt. Most of the dairy products I consume are traces in bread, Quorn etc.. I rarely eat cheese or eggs. So rarely that I couldn't say if they cause symptoms or not, because I can't remember when I last eat them. 

But yes, does this sound like lactose intolerance, and is it possible to 'develop' lactose intolerance or sensitivity? Or could it just be a lingering virus? I'm wondering if I have made my body develop an aversion to dairy by not eating much of it for so long.

It's very possible to develop an intolerance to dairy products.  It's sometimes connected with a bout of illness.  If you've noticed that the symptoms are worse after dairy products but better without them, then you're probably in the best position to judge.  A doctor might ask you to keep a food and symptom diary to come to the same conclusion. 

The acid test is to eliminate dairy products for a few weeks, see if the problem is resolved and then.... reintroduce them.  Sounds a little masochistic but if the problem doesn't reappear with the dairy products or if the problem doesn't go away in their absence then, logically, it's something else causing the belly-aches. 

Sometimes people can develop lactose intolerance after they haven't eaten dairy in a long time.  It was explained to me as " your body forgets how to digest certain foods"

Living with lactose intolerance these days really isn't too bad.  The simplest thing is to always have Lactaid pills on you in case you want to drink dairy.  They're relatively cheap and you can just get them at a pharmacy.  Another option is soy milk/yogurt/ice cream or lactaid milk.  Personally I prefer lactaid milk; it's a little sweeter than regular milk but I think it tastes better than regular milk.

Buy a carton of lactaid milk and try drinking some of that (or using it in your cooking)... if you do NOT experience digestive discomfort from that, and you do from regular milk, there's your answer... your body does 'forget' how to handle lactose if you don't have it for a long time, that's not unusual. Most people who are lactose-intolerant are okay with yogurt though... yogurt and cheese have much less lactose in them than milk.

I use to drink alot of milk and eat a lot of yogurt. After I had my gallbladder out last year I can no longer diegest dairy. I get really bloated and my stomach hurts me. The gastoenologist told me to try yogurt again, after I quite eating it for a couple months. The same thing happend. Your body can just change like that.

Lactose intolerance is when you do not produce enough lactase enzyme to digest dairy and if you were not eating much dairy for a while your body may have decreased production of that enzyme.  I developed lactose intolerance in my 20's, it took me quite a while to realize what the problem was.  I got stomach pain and some epic tooting when I would eat ice cream or milk.  I take Lactaid pills whenever I'm going to eat any dairy products and I rarely have pain or other issues anymore.  Good luck!