I completely agree with all of your experiences. I also get an MS-crash after aerobic exercise. Often I go for a 30 minute fast walk in the evenings after my son has gone to bed, and it can be cool or cold, but I still get the awful crash afterwards. It can even last a few days afterwards.
I have found if you persevere with daily exercise after 7-10 days the crash stops happening and you start to feel more energised - the real challenge is to make it through the 'crash' week and beyond. I keep coming down with winter colds so I'd just made it through the hard part and was starting to feel good about my walk 2 weeks ago but have had to stop for the last while. Hoping to get back out walking this evening!
RR-MS dx 1998 and Coeliac dx 2003
Tecfidera, Cymbalta, Baclofen.
EPO, Fish Oils, Vitamin D3 2000 IU, Magnesium, Multivitamin/mineral, Co-Enzyme Q10, Probiotics, Milk Thistle, Melatonin.