It must be worrying and upsetting feeling that your affection isn't wanted.
I think from your description of a boy who needs to follow you around everywhere and have an enormous amount of attention, he sounds quite insecure, which is normal for a child with his background. DS used to be like that, he needed to be near me nearly all the time.
With his new behaviour though, it probably is not possible to tell how linked it is to the issues he has already. Do listen to your mum instinct/gut - if it ever says "This isn't normal" then you are most likely right
How is he with things like tickling or physical contact which isn't kissing/hugging? You could try and find affection doing other activities/games which promote attachment without close physical contact. Anything which gets you laughing together, or having lots of eye contact is good. Will he sit on your lap comfortably without actually hugging and make eye contact? I probably would not force any unwanted kisses, but you could try other ways to get around that. Even making eye contact while rolling a ball to each other is good, doesn't have to involve touch. DS and I did well with little things like that, especially when he refused to let me kiss etc because he was grieving for his FC. I also used to say, right for the next 2 minutes, we are going to sit together and do nothing and just be close, which he hated at first, then really took to (still likes doing it now)!
If he totally refuses to allow you to do things (eg. bath or teeth brushing) Dad could try saying 'no I can't do that tonight, mummy will instead'. I suspect that might result in quite a bit of upset, but I knew a family who had to do that, and the child did stop refusing to allow their mum to do things. You could have Dad close by of course whilst you do it
And also, this is not a reflection of you as a parent. It hurts to feel rejected, but it isn't personally directed at you. Keep trying and hopefully it will get better soon :)