What Causes Sweating, Nausea And Migraine After Taking Viccodins And Methadone?

my bf takes pills on the daily, just never has taken them together at the same time. and he took 2 viccodins and 1 methadone and not even 30 minutes later he was sweating profusely, cold chills, nauseous and had a really bad migraine. especially a sharp pain above his left eyebrow and threw up as soon as we got home. he is really cold, yet drenched in sweat and has to keep switching sides of the bed to lay on because he is sweating so much and it is making him colder. do you know what is happening to him?? what may have caused this? or what we can do to make him feel better or more comfortable?