This is the first time you mentioned pain......is that what is adding to th nausea?....is that what they are looking for the cause of also? or is that a completely different issue from the eating & nausea problem?
Think if you are in pain almost constantly, that would be something they could find.
I had bladder infections constantly after giving birth.....that was painful....or there could be all kinds of reasons depending on where th pain is. You may even have something going on from after your pregnancy that needs taken care of
Oh, another FYI, my neighbor's 19 year old daughter is pregnant....she was on birthcontrol. My MIL got pregnant with her last child while she was on the pill 20 years after my husband was born...lol.....it isn't a guarantee at all...like you said...only guarantee is not having any relations.
Sure hope they can figure out what is going on for your health...know we care.

Debbie