Panic attack, over thinking it all, fear of depression.?

I smoked some horrible weed a few days ago which triggered a terrible panic attack, since then I've been pretty messed up. I fear I have depression and I'm also over thinking everything (Which I think it's what triggers my hypochondriac thought of "depression") therefore making me think, or rather, fear I'm going crazy. I hate this! I want to stop thinking this way. I feel very self conscious of everything I do now, because I feel its not normal when it shouldn't be this way. I also get raging headaches and some nausea, but I think that is due to this infernal anxiety. Has anyone felt remotely the same? Please help.