For one, you're definitely not around 4-5% BF, lol. If you were, you'd be ripped to shreds like the bodybuilders in your weight class... which obviously you're not.
The trip probaly put some fat on ya when you ate caloric excess because your body was in starvation mode. Nothing much to worry about.. it's not that bad.
In any case, yeah up the cals and start heavy lifting + metcon again. I'm curious what does your routine look like? I don't think it's healthy to try to gain back all that weight at once. I think most of it is water weight so definitely hydrate yourself, but trying to gain stuff back to fast is only going to put on fat.