How do I know if I have cancer help please asap?

See a doc. ...And chill. I sense a lot of anxiety in your question. You need to see a doctor for a good physical exam and if necessary, additional tests. If you have cancer, you will be sent to an oncologist for treatment. If not, he/she can address any anxiety issues you may have. It's ok to be alert but you can't live in fear. Best to you.