Posted: 24/12/2014 at 00:15
Just throwing in a few thoughts from a totally lay perspective.
Could the feeling sick/dizzy when exercising be a nutrition problem or maybe low iron, possibly as a side effect of breastfeeding?
How difficult was your labour? Thinking maybe it might have put more strain on your body than you realise. Have you monitored your HR during the day to see what is happening when you're not exercising? No harm in seeing your GP doesn't take
One other thought is that maybe you are just trying to regain your former form too quickly. Frustrating as it may be, perhaps you need to back off and go right back to doing a few more weeks of very short, gentle run/walk or even just brisk walking if necessary to keep your heart rate down.