After a small amount of exercise (for example lifting buckets to replace the water in my mum's fish tanks), I often get a rash along the back of my arms and chest, along with a hot flush, I also get the same after walking for a while and stopping. The exercise isn't strenuous in any way, I'm not out of breath afterwards.

It only happens when the exercise stops, and doesn't happen when I do exercise that gets me out of breath. The hot flush disappears after a minute and the rash after 10.

When I mentionned it to my GP he suggested it may be an allergy to something, but there seems to be no regularity with that.

I also get blotchy skin after taking a hot shower, although not the same as the rash it may be connected.

Any ideas?

Have you recently changed your washing powder? The reaction can occur after the body gets warm and there is more movement against the clothes, Blotchy skin after a shower I only go blotchy if the waters been to warm or the pressure was high.
Im sure there will be others that may well be able to define a bit deeper for you.

It happens even when I don't have a shirt on :|

I must add, it isn't itchy either.. just looks like a rash... raised bumps on the skin and redness

Hugs I hope someone can help you further I really don't have any other suggestions xxxx sorry xxxx

I'm thinking!!

How long has this been going on Cap?

About a few years- I've always been blotchy after shower but the rash is a new thing

It may be nothing more than your body's reaction to the slight exercise. You know how some people turn red in the face or get blotchy on the face and neck when they are nervous?

I don't understand why it doesn't show under more strenuous exercise

OOOO Cap maybe you just work through it and don't notice it coming and going when you do a full work out