Question: What injuries would be realistic after my character got beaten up?

Answer: Pretty much anything.

I know that isn’t a very satisfying answer but hear me out. The extent of your character’s injuries depends on so many factors that I, without intimate knowledge of your story, can’t reasonably tell you the exact extent of the injuries your character might acquire.

Let’s say your character gets stabbed in the abdomen. Depending on the length/sharpness of the weapon, the exact location of the wound, the angle of entry/exit, the force exerted, even how much fat your character carries around their middle, the injury could range from a mere flesh wound to nearly instantly fatal. Yes, some injuries are more likely than others, but you, the author, have a lot of leeway here. It’s your story. As long as you stay within the realm of reasonable, you can do what you want.

A few caveats.

• If your character is hit on the head hard enough for them to be unconscious for more than a few seconds, they’re going to have some brain damage. Even if they’re unconscious for just a few seconds, they’re going to have a concussion. If they’re out for more than 20 minutes, they probably have serious, permanent brain damage – they might even be stuck in a permanent vegetative state.
• If your character passes out from blood loss, they’re going to die of blood loss if they aren’t treated soon.
• You can’t put weight on a broken leg. I don’t care how manly your character is, he’s not going anywhere if he broke his tibia or femur (you might be able to get away with walking on a broken fibula).   
• Yes, gut wounds cause infection, but not for a few days. The more immediate concern is still blood loss.
• Your character will only cough up blood if their lungs, trachea, mouth, nose, or esophagus are bleeding. Stop having your character cough up blood after being punched in the gut.
• Stop wrenching broken noses back into place; your character is liable to do more damage than good. Nasal bones are bones and, like any other bone, they should be set by someone who knows what they’re doing. Bad breaks may even require surgery. Unless the break is making it difficult for your character to breathe, have them ice it and take Tylenol until they’re able to get to a medical professional (or a boxing coach) to sort it out.
• Canes are used on the opposite side of the body. If your character’s left leg is injured, they’ll use a cane on the right.