I Am A 24 Year Old Guy And Have Been

I am a 24 year old guy and have been struggling with lower back pain. I played a ton of sports growing up (football, hockey, baseball, golf, water and snow skiing ) so know what pain feels like with the lower back issues I had in these sports. I woke up yesterday morning with a cold sweat and this pain in my mid to lower back. I ended up calling in sick to work and slept 15 straight hours. When i woke up, my back was killing me still. I did party a bit this weekend, went to a concert on Saturday night and stayed out late. I played hockey outside all day saturday. I have been taking some weight loss pills to take off about 15 pounds. This is the first time I have ever tried these. Today, the pain has been weird. Lower to middle back. All left side which has come and gone all day. My back pain from athletics does not feel like this pain. I feel like I constantly need to take a poop along with a fever on and off. I have been stretching and cracking my back all day with no relief. What do you think I am dealing with?