Cannabis isn't a great anti-seizure med for everyone, EciRon, but I'm glad you get beneficial effect. In some, it can cause just the opposite response. Depends on the type of seizure disorder and which area of the brain your seizure electrical signals originate from, from what I've read.

Have you told your doctor about the lung/chest pain? Lung/chest pain isn't one of the commonly reported side-effects from Dilantin/phenytoin, but that doesn't mean it can't be a reaction people have. Most folks have side-effects related to their central nervous system, but there are plenty of other reactions possible in other areas.

Definitely share the info about the symptoms you're experiencing with your doctor or his/her nurse or nurse practitioner. Try and evaluate, too, whether you might also be having some anxiety that would contribute to that feeling of chest tightness/pain or whether the onset of cool/dry weather could be aggravating it, too. I have asthma and a heart rhythm problem, both of which can cause chest pain. Colder weather really aggravates my asthma and gives me a feeling of chest pain, especially with exertion like exercise. Just some things to ponder. Good luck!