Propafenone Hydrochloride and half hour

I am a 60 year old male with lung cancer but in other wise good shape. I was given Propoxy 100s for extream pain in my left sholder and muscles in lower right back. I took the pills every 4 hours as directed from 8am on the first day and by evening had some mild light headed feeling and very slight bluring of vision. On the second day I started at 8am with no problem and took another pill at 12 noon and apx. one half hour later went to mow the lawn. While mowing on a cool day I started to sweat profusely, very dry mouth and became mildly nausious with some light headedness. This cleared up slowly in about 5 hours. There was no sign of blood pressure or heart problem.

For the first few days (taking 2 100mg pills each day) I felt mostly dopey (stoned) and my vision got blurry at times, slight ringing in the ears, and slight pain in my arms. None of this was extreme, but worth noting. I was prescribed this "narcotic" for a slight groin pull.

Then ... on the 5th day, I took one pill around 8 in the morning and it helped alleviate some of the pain and then I took the second earlier than I normally would (2:00) and this is where the nightmare began. After about a half hour I started getting extremely dizzy (I did have lunch) and almost felt like I was losing consciousness. I forced myself to get up and walk around the office. My chest felt constricted and I had a very difficult time breathing. This lasted for several hours and was VERY scary. I had breathing problems all the way up to laying down for bed that night and fortunately the next morning, I appeared to be OK. I'm still kinda in shock and wondering what the hell happened.

I plan on letting the doctor know, I am not allergic to anything and have taken pain medication in the past (vicodin's, etc). I assure you advil will be the only thing going in my system from this point forward. Just be careful.