Does anyone get anything like this? Or Am i just going crazy?

Hello there, i'm a 24 year old women, (young women) i have two kids, 4 and 17mths, ever since i have had my youngest i feel like i've been going nuts. I used to smoke every day (b4 having him) and when he was born i went back to smoking (weed) i stared feeling "different" very much like a worried feeling in my heart, and belly, i gave it up as much i hated to do it. But now the feeling has still not went away, sometimes, i'm feeling like this 3-7 times a day, where it starts in my head, i get sharp pains, and feel sick to my belly, then my heart starts to race, and i feel like i want to cry, sometimes i get dizzy, and feel like my head is on a cloud or something. I'm worried that i'm going crazy, every day my head hurts and i have a headache, i dont know if part of it is b/c i'm worring so mush that i'm sick, ( i have somehthing wrong with me a tumor or something) i feel like my life is ending slowly b/c i cant do alot of things i once did, for example, last week i went to walmart, and had to leave b/c i felt like i was gonna trip out, sometimes it starts in my belly, thats how i know it's coming on, and then goes to my heart and head, i feel like i cant get enough air into my lungs! I just want to know if anyone else gets this, or am i really nuts, and need to sign myself in! I mean i 'm no where near the point of hurting myself or my kids, but i feel like i'm traped in some ways.....like i cant go out, b/c i'm to worried about not being able to handle it! CAN ANYONE HELP>???? I'm gonna go see my doctor b/c i do want to make asure there really is nothing wrong,,, with my head, maybe get a mri or cat scan or something done,,,,but i just want to know if anyone else has anything that happens to them like this???? Please help me