Why Am I So Tired??

I've exercised while barely eating enough (I know better now, no worries), while smoking, while eating terribly, and have gone hiking plenty of times at decently high altitudes and have never been unable to exercise for more than 30 minutes so I thought I'd come here and ask some of the pros here.

I recently moved from California to Washington to go to university. I went to the gym twice in the first week and found myself pretty much becomming very tired very quickly. The first 15 minutes were like normal, they were easy, got my heart going nice and fast, and sweating nor more than usual.

My lifestyle has changed in general from rather sedentiary to lightly active I'm guessing from just going to and from class and climbing up 3 stories to my dorm room. However before I left California I walked my dog daily for around 45minutes on cross country trails, and although I got tired I was never flat out exausted.

Could it just be stress or the sudden change in lifestyle? Or could there be something wrong? The only real thing I noticed that was really out of the usual is that my face got really bright almost cherry red when I worked out, and it stayed that way for a good while (20mins?). I'm a pretty pale person and while the snow and cold weather up here makes my cheeks rosy sometimes, for the most part my face doesn't get that red, even when I think I'm blushing like mad. By 20 minutes I usually have to switch machines to something easier or really try to keep going. What's going on??

I'm not a very high energy person by nature, but for the most part am best for my stamina. Even when I was overweight and swimming in high school for pre season training we would run 6 miles cross country and I was always one of the first to finish because I could keep the same jogging pace the entire time.  Getting tired like this is very foreign to me.

if its not normal for you & you've been active before with no probs, i would say see a dr. better to be safe than sorry. having no energy sucks! sorry.

Is there a drastic difference in altitudes between the two places?  I know that can affect stamina and your ability to keep your breath (when I traveled from here, New York, to Colorado Springs last Christmas, I would lose my breath walking up just one flight of stairs at my sister-in-law's house!).

I've sort of been wondering about altitude, as I'm sure I'm higher up here than I used to be back home. I've had altitude sickness before while hiking so it wouldn't surprise me. However it didn't really feel the same which is probably why I've been a little worried. I climb 3 flights of stairs multiple times a day to get to and from class and from my room. If it is altitude related, how long would it be before I get my stamina that I love so much back?

About a month, I think.

Yeah, I think it can take quite a while to adjust, if it is altitude.  One thing that helps some is drinking lots of water (according to my sister-in-law), so be sure to keep super hydrated!

See a doctor quickly -- you may suffer from sleep apnea.

Thank you for your concern jalanday, but I highly doubt I have sleep apnea, and don't think any sleeping disorders are effecting my ability to work out. I'm diagnosed with insomnia and am used to general daily fatigue from being unable to get enough sleep at night.

The fact that this is very different from just being tired, and is a lot more similar to exaustion in general was what sparked my initial concern.

I haven't worked out since, but I'm going to try some light exercise later this week and see how it goes. I donated blood today though so we'll see what happens.

Thank you all very much for your helpful replies.