Hello Ryana and welcome to UKCS. I can't really tell what has happened to your airbed from your description, but here's what used to work for me, until a feral child knackered our airbed by using it as a trampoline.
They survive better if they're used on a tent carpet or rug.
Because they're easily damaged in storage and transit, it's worth checking them all over for leaks as soon as you're pitched and before you get the first beer in. Tenacious tape and/or seam sealer works for the usual small punctures, but let some of the air out first so it doesn't blow your patch off. Give it a couple of hours for the adhesive to go off before pumping it back up.
It'll still get a bit floppier overnight because of the drop in temperature.
If the bed still drops you gently to the floor overnight, it's likely that the valve is leaking. This is quite common in airbeds with built-in pumps, because they draw dust into the valve seal. As far as I'm aware, only Aerobed (now owned by Coleman) supply replacement valves. It's impossible to get at the Intex ones' valves without cutting up the airbed. If I were buying one again I'd probably do something clever with the wadding from a dust mask to stop crap getting drawn into the valve, or get an Aerobed.
A self inflating mat + camp bed is more comfortable and reliable but more expensive, bulkier to transport and a guaranteed passion killer.
Haha iv got 2 feral kids and i find them 2 be the passion killer , thankyou for the info on the airbed, never thought about it before. Think i might suggest 2 singles, hope the boss doesnt get sad/offended.....