YOu could try a forced soak just go slow and easy as not to stress him out to much but get a tube with a lid put enough warm probably slightly cooler than you would make your bath water to cover about half his body height put him in and lid on make sure you have holes in the lid or sides first and let him sit for about 10-20 mins do not let the water get cold then open the lid and let him crawl out on his own and dont handle him for a bit he will need to feel safe and secure for a lil bit especially if its his first soak / bath always watch a soaking snake to ensure his head does not stay submerged in water when mine are going into shed I usually raise my humidity to around 70-75% and as soon as the shed happens let it drop back to 60-65%