Today I washed Calliope, you cannot imagine how dirty and how brown the water was! she was filthy! but she did not smell... and I had to use the soap twice! never happend before (now she is enjoying the floor time in the balcony outside, maybe this is the reason)
If I were you I would wash the piggie now, because her brown fur can hide residuals of wee and bacteria. Use a very delicate soap for newborns, or search on the net about the list of products and their INCI. There are natural good soaps for humans, better than the famous ones and the specific ones for pets. Soaps for newborns don't make any foam.
Then, don't wash him another time and if he smells again it could be his wee, rich of nitrates taken from the vegs for example. Maybe at the pet store he lay on his wee... Consider that a smelly wee might be a sign of infection... or something not normal.
Use a basin and a glass for (gently) pouring the water on his fur, don't do any noise. Afterwards wrap him into a warm towel (micofibre towels work better and absorb all the water), cuddle him, give him some treat and use the hairdrier (if he does not like it, use other towels... prepare a lot of towels before starting...). Very warm water, though.
When you find a good method he will enjoy the bath, but the first time for me ended up in a disaster
