Two positive, two negative now bleeding. Help

Hi, 

i have been feeling very pregnant as they say the last couple of weeks, sickness morning noon and night, back pain, nausea, sore and swollen boobs, dizziness and fatigue. So I took a test Friday which had a faint positive, then again saturday morning which was a stronger positive line. However I have taken two tests since which came back negative and this morning I have started bleeding. The blood started a brown colour which I thought could be implantation bleeding but has got heavier with some clots with mild cramping. I'm now panicking as we have been trying for a baby for 2 years.

Please does anyone one have any advice as to what could be going on or if anyone has had anything similar? Thanks in advance.