Am i pregnant? or is there something else wrong with me?

I've been feeling really nauseus and tired lately and had horrible stomach pains and really weird periods for the past couple of months. So in order to feel better I turned stupid and started using some drugs again lately like weed coke and speed, not a lot just a little every other week or so, I know that is very stupid so I'm not using anymore starting today, but out of nowhere this morning I woke up with red rashes and welts only all over my stretch marks on my belly and sides, it itches and burns like hell and I'm not wearing tight clothing or using new clothe washing detergent so idk what's wrong. I looked online and everywhere I looked said that its a pregnancy related rash wich is freaking me out because last time I had sex was four months ago with my ex and I think eather the condom broke or slipped off and ever since then weird things have happened to me, my periods are strange, my boobs have been sore, I'm nauseus all the time but I've lost about 27lbs since then started loosing weight before I messed with rhe drugs so I kno its not all coke n meth related. So my question is, could I possibly be pregnant or is something else wrong with me? Btw, I took a cheap $2 preggo test 2 weeks after I had sex with him just incase cuz he's already gotten 2 girls pregnant while they were on birth controll and using protection, and it came out negative. So idk, and I smoked the last of the speed I had last night and promised myself I wouldn't mess with those drugs ne more wich I kno I can do because before two months ago when I started using again I had quit drugs cold turkey for a year and a half on my own will so idk,please give me some adviice