The reaction you see in your pup is not unusual, these are pesticides, they are designed to kill/repel/sterilize/destroy their nervous system of the insects. Some pups are more sensitive than others and will feel the effects more than others.
Curiously, these potential side effects are not published in the literature accompanying the products, nor do many veterinarians know the dangers. But there are numerous anecdotal reports from veterinarians in the U.S. and the U.K. of dogs who were treated with spot-on products who have displayed signs of neurological damage, such as depression, lethargy, convulsions, underactivity, tremors, overactivity, stiffened limbs, and lameness.
A lot of the products at the pet store have pyrethroids /permethrins in them There's been a lot of pets injured or have died from the use of these. I would stay away from them........
2008 study by the Center for Public Integrity reported at least 1,600 pet deaths related to spot-on treatments with pyrethroids were reported to the EPA over the last five years. In April 2009, the EPA issued an advisory about spot-on products after receiving over 44,000 reports of adverse reactions during 2008, including 600 deaths. This represented a very disturbing 57 percent increase in reported incidents in a single year -- incidents ranging from mild skin irritation to seizures and death.
Battling these bugs on a "natural" level is a tremendous undertaking. Personally I have been using cedar oil on the pets and there bedding. I get it at Cedarcide. I have two little spritzers and then I buy a qt. to refill them. They do have a product for the lawn but I haven't tried it as of yet to see if it actually works. I do know the spray works, I sprayed a couple of fleas and an ant , they died within seconds.
CEDARCIDE.COM
Last year I started addressing the yard, as to tackle the source of the problem, I have been applying D.E. I can now buy an organig bag of D.E. at Menards. I used to buy it on line but the shipping gets pricey. I will continue to use this until I find some other methods.
About two years ago I did apply nematodes to the lawn. Since I can't actually "see" them I don't know if it's doing anything.I've found an acticle using dish soap in a hose end sprayer for the lawn but I have not tried that either so I don't know if it actually works or not.....
Dawn dish soap... mix 4 oz dawn dish-soap with 16 oz water into a liquid spreader (typically used to spread fertilizer on lawns) set concentration to the highest setting and spray lawn liberally (this will usually last 30 days unless there is excessive amounts of rainfall) and is much cheaper than lawn treatments for fleas.
Good luck on your bug battle. I have a feeling since we didn't have much of a winter and the warm weather is here already we're in for a nasty season....