Relax and calm down, you'll just add stress to it and make it worse.
I have heavy legs also with some burning feeling from time to time. Baclfen seems to help. But you may have to expriment with dosage. I used to take 1 every 4 hours, now I take 1 every 6 hours. so I think I would a good setting. Try to keep you legs cool. It's hard, I have had MS since 1993, A lot of people will give you different advice. Remain calm, use the advice from the members here and come up with something the works for you. Enjoy you trip. Like I stated, Rellax, stay calm, stress will only make it worse.