Please don't worry. You just had major surgery. There is swelling and your body is saying "What the heck". Just try to heal and it will come. Some weeks you will gain and some you will lose. It's all part of the process. You have to look at it as a 12-18 month process. I promise you in 12 months you will be noticing a huge difference between then and now. You got this.
Almost everyone gains immediately after any type of urgery. They pump you full of saline, which causes water retention. Don't sweat it. You'll be losing on no time.
Completely normal, don't worry.
You were pumped full of fluids, you just had surgery and your body is in shock.
It will pass and you will drop quite a few lbs quick. I didn't weigh myself until 1 week post op and had lost 11lbs from surgery day and then balanced out.