What can cause ALT levels to rapidly increase?

That means ur liver is working too hard. Your liver is what filters out the foriegn/artificial chemicals.

Thins like artificial colors/canned food.

Also, artificial scents from shampoo/cologne/axe spray etc, are foregin chemicals to the body, and will stress your liver to expel them.

Thats my only advice is to get rid of chemical cleaners/dont breathe anything unatural like paint fumes/plastic fumes/perfume,draino whatever. can effect you.

Also your doctor may be lying to you to convince you that you need some kind of pill. If you feel healthy, stay away from the doctors, for all you know, You could be just fine until you've been cramming antibiotics and vicodin down ur throat for years.

Any virosis lately? There are various of viruses which may attack liver and damage it even if you don't feel sick. It could be some pills you take everyday-like some vitamins or artificial sweetener or similar?
What about contraceptives-if you are a women ofcourse?
Where do you work-is it some kind of enviroment where you are exposed to toxic substancies?
Some antibiotics can cause high liver enzimes.

Anyway I would follow this and be careful.

Good luck. Take care.