I exercised three days and I have muscle pain I should exercise more?

Day of rest OK too. If you are just getting started with exercising or returning after an hiatus, you can expect some "startup soreness". It is ok to work through the soreness, and it is also ok to add a day of rest ocassionally. You might try alternating your regimen with 2 days of exercising followed by a day of rest. Nsaids (anti-inflammatories such as motrin, naproxen, advil) can also help with muscle soreness.
You should rest! You don't give a ton of information. However, I can give you some good general information about soreness. You need to listen to your body. If you work out and develop significant muscle soreness afterward, you need to rest and give the involved muscles a chance to heal. Otherwise, you will be subjecting yourself to a much greater chance of injury. Get some rest!!
See below. It is not uncommon to be sore after exercising 3 days. Try taking a day off to give you body some time to rest.
Take a break... Normal response, but give it a day or so on ice to make sure nothing is torn...