Is there a chance I might have cancer?

Okay , So I just had my gallbladder taken out and I should be okay by now. It's abnormal and I should be up and doing things now. But , I get so tired and just by standing up I feel my heart beat fast and I feel like I just ran a mile or something. And , I’m really weak right now and I’ve lost so much weight and I keep losing weight it’s hard to gain any weight. I had a mild fever and it’s hard to get up and do things. I get so dizzy and I get motion sickness. And I’m having joint pains in my knees. I have been pretty forgetful and it’s a little hard to concentrate. I have headaches daily. But they're a little different. And I just get so tired , I’ll keep falling asleep and I wake up but I still feel tired so I fall asleep again. Then I fall asleep around midnight and wake up at 4 am tired but still can’t sleep. I was on Google and I wanted to know if there’s a chance I have cancer ? My doctor isn't sure What’s wrong with me either. I’ve also been really depressed and anxious.