In my 99 Jeep Cherokee Sport, my tail light went out. A few days later, it started working again. A few days after that, the same tailight went out, but the brake light went out as well. The bulb is good, but I cannot figure it out for the life of me. Any suggestions? Thanks in advance

I have a 00 GC with sim problem. when u step on the brake
Only one side lights up and the other side goes out. All new bulbs in taillights. Extremely frustrating cuz mechanics in my area can't seem to help. Bought this truck to out my 7 month old in and it's one thing after another. If u solve your problem could use pls let me know. B thank u