Good luck, and if it doesn't get better when your period starts back up, talk to a parent/trusted adult and see a gynecologist or gp.
Ugh, a downside of being a teenager is the hormone imbalances and growing pains. It's common to have breast pain when you are growing or when your hormones are crazy. Shooting pains and soreness are typical around your age as are irregular periods. If you don't have a fever, redness or local swelling it is likely just growing pains and not any infection. The breast soreness can be aggravated by a few things, to help reduce pain try the following: stop ingesting caffeine of any kind (coffee, soda, tea, chocolate), cut out junk food, eat more fruits/veggies, and make sure your diet has a lot of calcium and magnesium and healthy oils like those found in fish. Exercise can also help. A good bra will make it easier, and you can try wearing a soft one without underwire if possible at night. If its really bad, cabbage leaves put in your bra is supposed to help although I've never done it.
If you were really sick it probably threw your cycle off and made your period late-I'd guess its nasty pms