I need to know something ?

i have hear about i cant be in the heator bath with hot water and im just coming acros that though and now i wonder why is that like what does the heat do to you if i might well just (might have ms what can the heat do to me i dont want any surprise bc i had a small systom like i was at the park last week and it was hot but i didnt pay mind to it but i did get very very very dizzy that ppl though i was drunk and i wasnt so therefore i want to know what happend with the heat with ms and wat are the systom that can happen with ms and the heat like i said i just though it now and when i was told of that well at the moment i wasnt paying attencion so now im curiose so i decide to ask here bc many ppl has help thru here and help with answering wat i need or wat i ask so plz plz if you have an answer me plz feel free to answer me ok it would help me out alot i dont want any surprises