Why do I feel bad when someone does something nice for me, specially if they buy me gifts?

You may have not a very high self-esteem, so you do not believe you deserve it. Working on accepting yourself, and loving who you are may help with the acceptance of gifts.

Maybe you are just being to harsh on yourself? Sometimes we all have feelings, for one reason or another. The best thing you could do is to have a sit down conversation with a trusted adult about your feelings. Perhaps that may help you?

There are various reasons as to why this may happen. Sometimes we may have bad experiences during childhood which manifest themselves as insecurity, which may drive us to think that we're not worthy of receiving this affection. It's important to remember, that different people have different perspectives, and one must keep an open mind about what others think; if someone does something nice to you, it's likely that they see you as a friend, or that they trust you.

You have too much of a mixture between self-pity and self-judgement, which brings you to the point where you feel bad for them because they care about you, and you feel like it's a waste of attention. Maybe, you reach the point where you feel that the other person is better than you, for caring more about you, than yourself. Of course the exact opposite could also be the case.

Because it feels like i must do something in return for them and i sometimes dont know what to do to make it up for them

This could possibly be a result of subconsciously feeling unworthy of kindness. Sometimes, particularly people that have been abused or traumatized, it can be hard for the brain to accept kindness, as weird as that sounds. Understand that your feelings are completely okay, but that it is also okay to show that person appreciation and thank them for what they have done.

It's normal! It's hard because you don't really know what to do when someone says they bought you something, you feel bad that someone spent their hard earned money! But I completely understand

Because it often gives you a sense of not being worthy of the gift and also engenders the feeling that you are now beholding to them -- both of which make you embarrassed. Receiving a gift gracefully is far harder than giving a gift . And its quite common-- to be honest , I've never mastered it myself ...

I once read that we can only accept the love and gratitude you think you deserve. Could it be that you think that you don't deserve it?

You may feel undeserving of those gifts. However, it is nothing to feel guilty about. People give you gifts because you have earned them.