Horizontal line on test

I've never been pregnant before and I've always been baby crazy. I'm 20 and I think I might be pregnant. I have taken over four tests and each have come out negative. I'm having back pain, breasts are sore, cravings, headaches. When I took the fourth test I got this weird horizontal line coming from the left to right. The control line came up normal  ( it's a cheap first signal test) please someone help.