Hi.
Thanks for your query.
Noted the history of being 7 weeks pregnant,
nausea at bed time, stomach pain in the middle of night, continued with burping and gas pains, had 3-4 good bowel movements, dry heaves a few times, worsened after taco salad,
anxiety is kicking, hard to relax...
All this history is indicative that you may indeed have a intestinal problem.
I would advise you the following since you are 7 weeks pregnant not allowing many a medicines in the normal course, but if it becomes mandatory, it may be needed to have an admission to the hospital for clinical evaluation, examination and your safety comes first.
Have an opinion of an Infectious disease specialist.
Also consult a Gynecologist to keep a watch and have an opinion in difficult cases.