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

There could be various reasons for it, also it depends which "bad" emotion precisely you are referring to. In general, I can think of two such reasons. One, you feel you are not worthy of good things in life. It is possible that you have picked up that belief somewhere in life, either from a parent figure or someone you really trusted in your life has made you feel that way. Being grown up now you don't necessarily remember when you started to feel that way or what lead you in this direction of feeling unworthy. It doesn't have to be a big traumatic experience like having absent parents, it could be simple comments here and there of how not good enough you are, which can also pull you down this spiral. The second reason could be that this specific love language of giving gift is not one of your preferred love language. It may make you uncomfortable and especially feel bad if you start to feel like you are mooching off someone. I just thought of one more reason, you might be dealing with somewhat of an imposter syndrome kind of feeling, where you may feel as if you are deceiving someone and that had lead them to see you as this amazing person whom they want to shower with love and gifts, but all you can feel is that you have manipulated them into feeling this way. I would recommend naming what emotions come up when you feel bad about it to help you in knowing what underlying reasons could be. Ask the whys.

Everyone's love language is different, which is why someone doing nice for you or buying you a gift might not feel good. While that person might think that their act of service or gift will show their love for you, you might feel guilty about it, not be sure how to react, or otherwise feel uncomfortable. While you probably can't change their way of showing affection, you can dive deep into your personal feelings and love languages. Knowing what your love language is and what your friends and families are can help you understand what you are looking for from others and why they are making you feel bad. Then you can communicate that with them and hopefully feel better!

A lot of the time, we as people can feel guilty when someone buys us gifts. Often it can be, but not always is, a feeling of imposter syndrome, feeling unworthy of the gift. You may feel guilty because you feel like you have to repay this gift so it feels equal and fair, but often times people can just be nice for the sake of being nice. Some people have no ulterior motive behind giving you a gift, and it can be hard to fathom, especially if you grew up hearing the saying "nothing in the world is free". In fact, some people find it easier to express themselves through gift giving. When someone gives you a gift, it could be that they want to show you just how much you mean to them.

You might feel burdensome sometimes at the receiving end, but you can focus on why you feel comfortable with people doing good deeds for you over time. Thus, focus on how uncomfortable it makes you feel when you are at the receiving end. I'd suggest to look at these aspects in figuring out why you feel bad. 1. Your relationship with the one who does the giving. 2. Your current emotions when you are put into a situation of receiving. Though these are subjective, human feelings are often indescribable. Whatever you are feeling, be it bad or good, it is always justifiable.