Has he been checked for PID? Here is a link:
http://www.isitpid.com/
Has he been cultured for strep? When checking for strep (and it should be checked for with EACH fever!!!), he needs to get both a quick swab and a 72 hour culture.
How about Kawasaki? Have they done an EKG to check his heart at all? This is a big one. If this has not been done, then it needs done ASAP!!
Does he have symptoms with the fevers or just the fevers? Are there any corresponding mood changes that would NOT be typical of a 2 yr old? For example, does he seem OCD about anything or have super stress or excessive separation anxiety? Does he act BETTER when he's sick than he does when he's "well"? These can all be signs of PANDAS which is an autoimmune disorder related to strep. My daughter has this and she too had frequent high fevers from a very young age.
The cold, hard truth...
-If your dr doesn't help, get a new one. You may have to pay out of pocket. Children's hospital doctors have been our best bets.
-Get a chiro. Kids chiropractic is gentle and helps build up the immune system.
-Get on a whole-foods diet. NO junk! Everything you eat shoudl be coming directly from the source. Nothing apple-flavored- eat the apple!! etc.
-Research diets for kids with similar issues. Look at the GAPS diet, SCD diet, Feingold program, celiac, leaky gut disorders, etc. Even if he is undiagnosed, my bet is that he has an underlying autoimmune disease. This isn't the end of the world, but he needs some extra support to stay well. You can direct her to my eating blog if you want: www.chickiepea.wordpress.com to read our story too.
-Allergists aren't that helpful. My kids have food sensitivities and environmental sensitivities that allergists haven't detected. We had MSA testing through HomeFirst and do muscle testing (also called NRT or nutritional response therapy) with excellent results!
-Get rid of toxins in the home. Start small and cull the toys with BPA, quit using chemicals to clean, and then move on to big things like ripping out nylon carpeting, etc.
I hope this helps. This is the "short" list of things I would try. If you (or she!) need any more ideas, I'm happy to brainstorm with you. I've been there, done that, so I know how exasperating it can all be.
Hugs,
M.