From all the screenshots i provided, means i won't know at at all who gave the sudden payments?
Are those being received from the same address?
I'm thinking that you may have left the address as a withdrawal address on a 'BTC faucet'
or an 'altcoin mining service that pays in BTC' that has auto-withdrawal feature and it may be profit from your referral(s).
I can't think of any other passive BTC income that a user can forget that easily.