I had that same issue in my second trimester. I was allergic to the iron in my prenatal pills try eliminating that, I take prenatals without iron and I've been doing great. I went to a specialist and no doctor knew what the issue was until I eliminated my vitamins one by one for a few days.
I hope this could help! It's very common one of my friends had that same issue.
This probably doesn't help but my husband recently had a series of allergic reactions. We finally found out (conclusively I hope) that he is allergic to Xtra brand laundry soap. I had bought it because it was super cheap but its not what we usually get. Consider environmental things, not just food. But with your journal I imagine you are doing so... hope you figure it out!
I did with my first pregnancy. I would get hives and it got so bad one time it was interfering with my breathing. I never did find out what was causing me to have a reaction.