There have been a number of repeated reports from MS sufferers stating that their conditions worsen after consuming dairy products derived from cows. I have personal experience of this, having decided many years before my MS diagnosis, that I could not tolerate cow's milk or dairy products. Following my diagnosis I took the decision to move to a fully vegan diet and now only consume nut and oat milks and products.
In multiple sclerosis, the body's immune system destroys the myelin sheath. Following clinical trials, evidence suggests that various proteins found in cow's milk trigger similar reactions in the body and bring about perforation of the myelin sheath. These include Butyrophilin and Bovine Serum Albumin (BSA) This is actually due to antibodies in the body trying to attack and remove the 'foreign' proteins, but in so doing they also attack a natural human protein (MOG), which appears very similar to the cow's protein, and which is needed for healthy stabilisation of myelin.
The caveat is that this only affects MS patients who are allergic to cow's milk and there is not currently a test for this. Those affected develop an allergy to certain cow's proteins as a result of consuming milk. Then, as soon as fresh dairy products are consumed, the immune system produces masses of antibodies. But due to the similarity mentioned above, these antibodies also damage the myelin sheath around the nerve fibres.
An easy switch is to substitute cow's milk for nut, soya or oat milk as all are readily available nowadays, as are cheese substitutes (Applewood vegan, Sheeze, etc) and many yoghurts which are either soya or coconut based. Take a look at my 'Gallery' page for some recipe inspiration.