[snolan]

I haven't been on the same meds as you but being a cyclist and working in the health field I can offer a bit of advice. You may want to purchase a heart rate monitor. It will give you a better idea of just how hard you are working. The fact that you are just getting back into things and with the other factors, staying within you target heart rate range is important. Even if you don't have a heart condition your heart is a muscle and requires the same fuel to operate. So if you are dehydrated and anemic it will not be receiving the fuel it needs to function at a high level, and it will tell you in the form of chest pain.

You can get HR monitor at any sporting store. I use Polar brand they have a range of prices, the more you pay the more stuff it tracts, ie calories and such. I would still mention it to your Dr. of course, but it may just be that you are working at to high an intensity especially if you are pulling your child in the trailer that doubles your workload.

If you don't know how to figure your target heart rate just google it there are a coulpe of ways to do it, just simple math.