heat intolerance

I have recently been on a weeks holday to Turkey where temperatures where reaching 30+ daily and my mobility seemed to be better, upon my return to the UK i spent a couple of hours in the back garden and struggled to put one foot in front of the other, i am intrerested f anybody else has experienced anything similar, i am well aware that any rise in temperature can cause worsening of symptoms but i am at a loss as to why i did not suffer with. the higher temperatures overseas., could anybody shed some light as to these strange circumstances… thank in advance for any responce…Colin