Can you have multiple cancers at a time?

Yes: People can develop multiple different cancers at once. This can occur by chance, because of exposures to things that contribute to the formation of multiple types of cancer like cigarette smoke, or rarely in patients with an inherited predisposition to getting cancers. For example, i recently saw a patient with rectal, bladder and prostate cancers all at once.

Yes: This is, fortunately, uncommon. It is more common for one cancer to spread to multiple areas, but there is no law against having more than one type of cancer at a time (though i think there should be!). I see you have blood in your stool & are coughing blood; while these can be caused by cancer, they are much more likely to have less serious causes, especially at your age.