Large red bumps on my neck and stomach that itch terribly. thinking spider bites or allergic reaction. am i on the right track here?

Hives: You are on the right track. It could be from a variety of causes. It could be spider, insect related. Other possibilities include allergic reaction, contact dermatitis, food reaction, and drug or medication reaction. Some people get urticaria of uncertain cause(idiopathic). A lot depends on exactly what the rash looks like, so best option is to see your doctor or a dermatologist.