Does your state recognize student designations, such as SPT or SPI? If yes, the answer is to refer this person to a HCP. If no, use your best judgement. Remember that your student status makes you vulnerable with required supervision, etc. It doesn't matter what you refer to it as or call it. I'm assuming that if he needs help with mobility, it will be legally defined as "rehabilitation", requiring a medically skilled service versus habilitation or conditioning, which a personal training certification would cover if the situation was concerning a non-medically involved client. Insurance will only cover you as long as you stay within your scope. Stray and you're 100% liable. Also, you better check your state laws about fee for services if you're planning to charge.