First. Before you go jumping to any conclusions and working yourself up into a state. See the doc, get the scans, go from there. It could be a million things or nothing serious at all.
I had an aquaintance who's just recently beaten Hodgkins Disease. He had like 11 tumours from his chest to his neck. He went through a bout of Chemotherapy and seems to be doing fine now. They say given his age he had quite a good chance. To my amazement he smoked cigs and weed like a chimney whilst he was having treatment. I personally thought it was stupid and would cease any extra intoxicating activities whilst already poisoning your body with chemo. So I reckon worrying about medical marijuana is the least of ones worries whilst going through cancer. It'd just make you think too much about it anyway imo. I'm aware it stimulates appetite and such.
There is natural alternatives to beating cancer. Many believe we are able to cure ourselves of anything. Wether all of us can harness that power in such times of distress is questionable imo. It's up to you what road you want to take. I know of people that have had huge success through vibrational healers, one I knew personally who had lymphoma seemed to be doing really well, she tried a diet from this website...
The Gerson Institute - Alternative Cancer Treatment
It consisted of something like 13 fresh squeezed vegetable and fruit juices a day and nothing else, it was strict to say the least. She went into remission several times, held it off long enough to see her little boy grow a few more years. She also had chemotherapy at other times. But unfortunately the cancer eventually got her in the end and she perished. So that doesn't say much aside from the fact that both kinds of treatment seemed to work, for a while. But her time was obviously up.
There ain't much more I can say other than good luck and hope it turns out to be nothing serious.