Every time I lay down my tooth goes to throbbing real bad but as soon as I stand up its fine y is that and what can I do to get it to stop I can't afford a dentist right now and need help I can't sleep its starting to affect my work and I need to support

Can't afford. I'm sorry, there is no OTC cure. Tooth is probably infected. Analgesic and/or antibiotic will only temporarily dampen the pain as the infection spreads. The more it spreads, the harder to treat, the more dangerous to other organ system, and the more extensive and expensive treatment becomes. Please don't put off treatment.
See your dentist. You have a problem with your tooth. You need to bite the bullet and go see a dentist. You may use advil (ibuprofen) and warm salt water gargle until then.
Inflammation. The bone around that tooth is inflamed. When you lie down the blood pressure in your head increases, causing the throbbing. You'll need to find a way to be treated, by either going to a clinic, dental school, financing your care, or borrowing money from friends or family. You can't treat this by yourself. Soon the pain will be continuous, and the advice will be the same: see a dentist.
Free dental care. Call your Local Dental Society for the information about free dental care for low-income population in your area. Take care.