Azathioprine side effects? Or something else?

I have been on 100mg of azathioprine for two weeks. I've been taking it when I get up, around 5am. The last 3 or 4 days, I've been experiencing some pretty good fatigue in the afternoon - starting around 2 or 3pm. Yesterday, along with the fatigue, came some stomach discomfort and general body soreness.

The stomach discomfort felt mostly like I was very full, even though I hadn't eaten more than usual. A week ago I started taking greens powder (1 tbsp), potato starch (2 tbsp), and psyllium seed powder (1 tbsp) in the morning (with two glasses of water), so I don't know if this could be the cause of the discomfort.

Anyway, today I have been feeling fatigue (worse than before), chills (it's 72F, but I have a sweatshirt, hood, slippers and a blanket on), stomach discomfort (same or slightly worse than yesterday), and body soreness (worse than yesterday). I feel like I have a fever, but I do not. This all started much earlier than yesterday, around 9 or 10am, and I haven't eaten anything since I had an english muffin for breakfast.

Does this all sound like side effects of the azathioprine? Or something else? If it's something else, when do I start getting concerned?

Thanks very much!

I know I'm fatigued all the time. I've been on Imuran for a year now.

Does sound like ulcerative colitis to me, not side effect from Imuran. UC has like a billion different types of stomach discomforts that can pop up, it's not like it's just your colon being a little ill. The whole system gets pretty fckd up from this disease.

Best of luck with the aza. Hope it gives you the relief you need!