electrical problems, Help!

Got a 97' tahoe 4x4, that both reear turn signals aren't working. At first the signals would blink faster then normal and then as time went past both signals would blink but the indicator by the gauges would still blink as if they were working. I check all the fuses and all appeared normal, then I took apart the rear assembly and found one bulb on both sides blow out. Replaced all blubs just to be sure and found that only the passenger side worked but still blinked at a fast pace. The only thing that works on both sides is the reverse light. please help, very faustrating.