Do I have an ulcer or IBS?

I am a 38 year old female. I woke up a week ago with diarrhea. For the next 24 hours I was sick on and off with diarrhea and a migraine. I was incredibly weak and nauseated with no interest in food at all. I was on day 10 of my period so I blamed it on hormones. I even made an appointment with my GYN to have my hormones tested as my periods have been terrible. I have not received the results of that test. My period has finally ended but a week later I am still very nauseated and weak. My appetite has returned somewhat within the last couple of days. However, soon as I eat I am running to the bathroom. I experience waves of burning pain in my lower abdomen and lower back, usually the right side. Sometimes I will poop and at this point it usually is not diarrhea. I have not noticed any blood or tarry stools. I bought some Zantac yesterday but I am sure it hasn't had time to take effect. I am wondering if I have h. pylori bacteria or if I just have IBS. It just started out of the blue which makes me think it could be h. pylori. I really just want to regain my energy and knock out this nausea and weakness. I need to get back to 100% at work and home and I desperately do not want to spend countless sick days at the doctor's office going through tests. I have read so many people's stories where they were misdiagnosed or not diagnosed at all. I could live with the bathroom runs if I could just knock out this nausea and regain some energy. Is there something I can take over the counter or foods I should avoid?