Every time I eat I get an extremely intense splitting headache?

I recently went to the doctor for a swollen lymph node. The antibiotic they gave me was so strong it gave me Thrush, (a yeast infection in the mouth). I was prescribed nystatin and now every time I eat, or drink, I get a sudden splitting headache that about brings me to my knees. Its happened when Ive eaten yogurt, pudding, and cottage cheese, I never had a dairy problem before this, in fact I was drinking milk yesterday no problem.. but i only took 2 bites of yogurt before it happened, same with the pudding. I don't know if its the medicine or whats happening but I was hoping someone would know. Please help!