Does implantation feel like a sudden throbbing pain? faint line on hpt?

i am trying not to drive my husband crazy! This month i have a very strong feeling that i am pregnant because shortly after ovulation i started to get nauseous, my are fuller and sore, and i was getting off and on twinges/cramps (same experience with my daughter). Yesterday i was feeling small cramps then all of a sudden a BIG one that made me stop what i was doing. An hour later i had brown blood and today its stopping, but it was a lighter flow..not period-like. I am due for my period tomorrow. Today i took a EPT and there was a slight faint faint line immediately but you have to look hard to see it. What do you think? I feel like i am going CRAZY over this. I really feel like i am!