What is goin on with me?

Ok so this might be a little weird...but I have started to notice (and have for awhile just didn't really think anything of it) that my stomach is getting hard. But it's not hard all the time but it's starting to stay hard? (to me it's confusing) Like you can push (not hard) on it and feel something in there...but at other times you can't feel anything. You can really feel something when you push closer to the top of my stomach, like something round..and it hurts when you lightly push on it. I can't lay on my stomach without getting an aching pain. My back is really starting to hurt and I've been having problems with my ribs (it's only a couple in particular that feel like they keep trying to break or spasm or something). I've taken two pregnancy tests ( June 27) but the first one didn't work so I took another one later on, the second one said that I wasn't pregnant. I had my period June 16th, didn't last that long. My chest is getting extremely sensitive to everything too...but I just don't know what the heck is going on...the past three weeks I've really not been feeling well. I can't seem to eat anything without feeling sick, and it's the same with drinking anything (even water!). I've been having a lot of different mood swings too.