Not all tick bites cause lyme, but if he got lyme a z-pak is not adequate treatment so he likely has chronic lyme.
Ticks can also transmit babesia, bartonella, rickettsia & other serious infections. These might be causing his problems & his problems might be unrelated to the bite. He needs a thorough medical evaluation including a doc knowledgeable about lyme & co-infections. See www.Ilads.Org.