Water not working at all through city, but it's on outside.

Our water outside at the spicket. The elbow shaped thing on the outside that hooks the water hose to the 5th wheel isn't clogged. Our inside water (bathroom and kitchen) comes on for about 5 seconds, tapers off, then no water. Soooo, we put water in our holding tank. When the pump is turned on the water works. When the pump is off and the water is turned on, the water that comes through the cold side is hot although not scalding hot. When the pump is turned on it runs cool through the cold side.

Additionally our kitchen sink is stopped up and I've put the chemicals to break stuff down in it to no avail. It's been this way for a month or more. It drains but not normally. And the smell is like rotten eggs when it bubbles back up. Right this second though it's not draining at all. We have 3 tanks on this 5th wheel and the kitchen thing is always left open so it's not like we're forgetting to open it. This is very frustrating. I have zero idea where to begin and honestly cannot afford a ton of money to hire someone to work on this stupid thing.

Edit:
Also I failed to mention in my earlier that the check valve has been deleted, so it's definitely not that.