Is It Food Posioning?

Two days ago around mid afternoon I began to feel tired, sore, and nasuaus. I was barely able to function I felt so ucky. I slept for almost all of the next day and once I snacked on small foods like tortillas and veggies I felt better, yet continued to have a headache that no OTC pain reliever could cure and neck soreness. I researched and found that I most likely caught food poisoning. Now I'm wondering if that's really the case. It's now been 3 days and the headache is gone but the neck soreness is still there and without any triggers or onset after a small dinner (mashed potatoes and a roll) I vomited everything I had ate for dinner not even 10 minutes after finishing. I've restricted myself to clear liquids and juices as if it were food posioning still but I'm wondering if maybe my self diagnosis is wrong. I felt pretty much normal minus the neck pain today and while eating wasn't bothered yet still fell Ill after eating minimal amounts of food. My friend jokes that I may be pregnant but all of my periods have been normal and on time, as well as I am also on birth control. Any insight on this situation would be of great help!