Left hip pain?

My left hip is in absolutely agony after a long walk or run. It’s usually okay when I’m on my feet a lot during the day at work but sometimes aches when I’m going to bed. I’m a left side sleeper but it’s been hurting when I lay on it at night too. It’s gotten to the point where I have to take a couple days off after a run or long walk because I’m limping and end up taking pain killers 3x per day which sometimes helps. Just asking for any advice before I go see a doctor?