Hey hey Lilmiffy, x
I know quite a few peeps who struggle with their HMS in the heat, so you're not on your own hun. x I get a bit looser, but if my joints come out easily, they go back easily, it's more of an annoyance for me than a massive problem so long as I keep hydrated.
If I get dehydrated, which I do stupidly easily; like a sponge in the sun, I really do over-heat and it's horrible. I can't cool down unless I have a cool shower and that doesn't last long at all. I drink huge amounts in the hot weather, very many pints, and that helps me a lot. As does a rehydration drink I make with half juice, half water and a touch of salt. My body absorbs that more easily than plain water, and it replaces some lost salts and minerals. I also like to fill my plant mister with cold water and spray my legs to save my body the effort of making sweat! Lovely when you sit with a breeze
on you.
Interestingly (or not if you're not into that kind of thing!

), the body's temperature sensors that decide whether to make your body heat or cool itself are in your neck. So if you have a cool neck and hot body, your body will feel the cool and work to warm up your whole body just because your neck is cool. Apparently the temperature of drinks can effect this too, so an ice cold drink can cool your neck, which could then make your body warm itself. Sounds really wrong doesn't it?! So...

maybe you could try wearing a scarf and drinking lots of nice hot tea... Or maybe not!

I love hot drinks any time, but I've never tried a scarf!
Hope you find something that helps soon love x
S