Just being gone for 2 weeks would not produce unusual skinniness if your snake did not eat those two weeks.
If his skin is kind of loose and hanging, that might be an indication of dehydration.
In all, no one here is qualified to suggest anything beyond recommending a vet appt for your snake as soon as you can given that the snake seems to have gone downhill very rapidly.
I would urge you to not wait until you have a chance, but rather to get your snake to a vet ASAP.