Problems regulating body temperature
Beyond heat sensitivity and Uthoff's phenomenon, MS patients may have difficulty regulating their body temperature due to impaired neural control of autonomic and endocrine functions. The part of the brain that senses core body temperature and regulates it to about 98.6° F — the preoptic anterior hypothalamus — can be affected by MS, allowing for atypical fluctuations in body temperature.
Hypothermia has been documented in small numbers of MS patients with core body temperatures ranging from to 86° F to 95° F. This can be problematic for patients when serious infections may be masked due to the absence of a typical fever response. My ‘normal’ body temperature runs closer to 95° F, so a temperature registering 99° F is more similar to 101° F in a healthy individual.
To sweat or not to sweat
When we become overheated, our bodies try to help by sweating and increasing blood flow to the skin. People with MS might not sweat as much because of impaired nerves that control normal thermoregulatory responses. However, they may experience greater increases of blood flow to the skin as compensation for impaired sweating.
Personally, I find that I sweat much more easily since developing heat sensitivity. Even a small amount of exertion will cause a slick back and damp shirt. This reinforces that everybody’s experience will be unique.
Cold sensitivity and MS
Some people living with MS may be more sensitive to cold temperatures than heat. Their symptoms get worse when the mercury falls. If this is the case, it’s important to try to keep body temperature steady, without overheating. Wearing layers of clothing, scarves, and/or wrist warmers may help, particularly if you also have Raynaud’s phenomenon.
Raynaud’s phenomenon and MS
Raynaud’s phenomenon is a condition characterized by discoloration in fingers and/or toes after exposure to changes in temperature. The tissue discoloration — which can range from purple, blue, red, or white — is typically caused by an abnormal spasm of blood vessels that reduces blood supply to the fingers or toes. Raynaud’s is commonly associated with connective tissue diseases, such as rheumatoid arthritis or scleroderma. But in an unusual case study, Raynaud’s was determined to be the presenting symptom for a person without a connective tissue disorder who was diagnosed with multiple sclerosis six months later.

All this time spec has said I had ms with scleroderma but it's more like ms with sjorgens because food doesnt taste the same, Raynauds. Sjorgens deals with the smaller periphial nerves. The problem with heat especially when/ if youre going thru the change. Menopause women have hot flushes. With MS I'm hot all the time even when my hands and feet are freezing. So in the hot weather I overheat to the point of having fits. That's what happened a few years ago. Now I know I have to live with the air conditioner which affects Raynauds. With my MS I suffer alot of stiffness in my spine after spasms. And it's like I have the flu when I'm having a bout. I can't handle blankets even in w inter.

The overheating! Bain of my existence, especially during the summer. Sleeping I overheat often several times/night. Use only 100% cotton sheets and if it's bad, sleep on a bath towel so when you wake up soaked, you can toss it on the floor and have a dry bed to sleep in. Keeping a fan on overhead helps a lot. Lots of water.

So sorry, it is definitely bothersome.
My tolerance for both heat and cold has changed drastically.
I use to stay outside working in my yard, garden etc all day long never bothered me.

Now when I go outside I start feeling overheated, thirsty, and nauseous within minutes.

Even inside it hits me and I will have to rinse off in cool water and put on dry clothes due to sweating so much, especially at night.

The neurologist told me it was due to the MS.

I'm always hot. I got a cooling vest and a cooling kerchief. It seems to help.I have my AC at 68 degrees abd a fan constantly running