Benadryl is to make them sleepy and sudafed/decongestant is for ears. I've used the infant drops when my son was 6 months but didn't use them at 2 years or at 2 1/2. If you plan to use one, I'd try it at home first to see how he reacts!
Benadryl doesn't come in a dosage form for kids that young. You'd need to buy the liquid and have your dr or pharmacist find out the dose for you. It's very small.
I gave my son gerber fruit chews a couple of times. They worked well. I was afraid the sugar would be a problem but he was fine.
For myself I use one sudafed (or generic). It makes me a little sleepy (makes most people hyper).