Suggest Remedies For A Thigh Muscle Pull

My husband was doing some a very physical exercise using a kettle ball by lifting over his head. he heard something snap and continued to exercise. by the second day, he had a muscle spasms in his thigh. and a pain in his lower left back, right above his butt. he is now experiencing a numbness in his shin and his left three fingers. he is 42, a truck driver and was an athlete years ago. he saw a chiropractor and he said that he will pulled a muscle. how should we treat this while he is driving for 14 hours a day.