Chest pain. These be signs of cancer?

So here's the thing... I quit smoking cigarettes quite a while ago and got addicted to Nicotex but I still am smoking weed(almost everyday)... It was fine until yesterday when I decided I'll smoke a cigarette(Marlboro Advance) I smoked 2 in the morning and it was fine until then too but things got worse after I smoked a cigarette in the evening! It felt like I had a lump or maybe something stuck in the back of my throat... At night I smoked a joint and started sucking on pulse candy and that's when I realized I had ulcers in my left gum which hold the molars... And the condition hasn't improved but just gotten worse because now I am unable to breathe properly when I lie down on my left side and even have a weird kind of pain in the chest(left side)!! I looked it up on google but couldn't find anything so I thought if you guys could help... I am afraid to go to a doctor for I might be diagnosed with cancer and might screw up my exam on 7th! Could these be signs of cancer?