I have tried using skrill, that is our medium of transaction when I trade my little amount of bitcoin in my friend from other country he uses it to send me the traded amound, I got a problem with my withdraw but their customer services is quite good! They assisted me throughout the process. I think they aren't phobited selling bitcoin? Because that is your source of fund. Maybe you can say that you gain your money thru online trading? You don't need to tell everything, because if you willl? You will be more suspicious.
I'm pretty sure Skrill doesn't prohibit crypto-related transactions on their platform because they actually allow you to add funds to your Skrill account using Bitcoin and Bitcoin Cash according to their own FAQ (click for link). If you really want to say something about your transaction, just make it short (and don't say anything at all in the case of PayPal).