I've had everything from very heavy to barely noticeable, painful to imperceptible, but mine were always irregular so never mind that.
So it could be nothing, or you could be still getting over your illness. (Perhaps your uterus lining wasn't very thick this time, because you'd just been sick -- it sounds like the latest one was forming while you were still ill or recovering.) It could be something as simple as stress (mental or physical).
Recent weight loss could also do it (fat is involved in estrogen production).
You might want to get a home pregnancy test anyway, just to rule it out (if it's, you know, possible).
Find a list of symptoms of
hyperthyroidism and check it over, though that's pretty unlikely.
If you're still concerned, you get any weird symptoms or pain, or it persists for another couple of months, call your doctor.
Did you find this post useful?

2

3