Question: help whats going on :/

I'm 4 days late with alot of pregnancy symptoms. First is the usual sore breasts, sore head and feeling abit sick. I have also had diarrhoea for 3 weeks. The doctor can't put his finger on what it could be. I took a test the other day and two lines came up but only half of each? So I waited a while an took another which was negative. By then I couldn't stop thinking I'm I or arnt I so I took a clear digital blue which came back not pregnant. I've took two more since then and I believe I can see a very very small faint line on both. Am not on no birth control either. Really want to know if my brain is making all tho up or am I really pregnant?