If he is that reactive that he needs all of those things, then you might want to consider checking into allergy shots. My son, 11 yrs old, has suffered from almost year round sinus drainage and sneezing for a few years now. Not severe, but it seems to get worse as he gets older... he definitely needs more tissues anyway.
He too tried Singulair way back when (he was about 7 yrs old).. and did not tolerate it very well (after a few weeks on it, it gave him a stomach ache every time). Then Nasonex. Stopped having any effect quickly. Then we went to Alavert/Claritin (loratidine) and that seemed to help some for awhile. Then it seemed to be less effective. We recently found a new doctor, and he switched him to Zyrtec, and suggested that when/if it begins to lose effectiveness to switch back to something else for a week or two, then go back to the Zyrtec again. That over time the body gets used to it and they can lose effectiveness. Rotating the meds can help with that... but ALSO, he suggested the shot therapy which we decided to follow up with. We did a blood panel and found that our son is allergic to around 14 different things (plants/grasses/pollens/molds) and that is why his allergies go almost year round. There is almost always something in the air that he is allergic to.
The big thing with the shot therapy is that, according to our doctor, as you get older (think teenager/adult) the allergy shots have a lower success rate. In other words, at my son's age, the success rate is around 85%, but if he waits another 10 years to give it a try, the liklihood that it will work effectively goes down to around 60% or so. AND, as an older person the therapy takes longer as well. For our son, a year and a half is expected (shots twice a week for the first couple of months, then once a week for a while, then once every 10 days, until a maintenance dose, etc etc). For an adult, that time becomes 3-4 years.
We always thought of the allergies as just a nuisance that he/we have had to deal with. But he had an asthmatic attack this week (never happened before) after working out in the yard bagging some leaves and then doing a pretty rigorous workout within a few hours afterwards. Possible molds from the composted leaves and then exercise is apparently what brought it on. Doing the shot therapy will certainly lessen the likelihood of another attack in the future. And after the costs of the initial creation of the serum he will be injected with, the costs for the actual injections will end up less than the $ we spend on tissues and OTC/prescription allergy symptom relief.
We are going for a "cure" not symptom relief. Finally. It is something worth checking into if your son is highly allergic and miserable.