Problems with speaking to people

Hi i am a 25 year old male who is a bit too shy and i believe i have a problem with my speech. I will buy something at the store and the cashier will say hi to me but i dont respond because i am insecure with my voice. My voice sounds rather.. faint. When i speak sometimes it sounds like a frog dying. For example i was at the gas station and this cashier who ive seen before a few times was acknowledging customers but when he saw me he didnt say hi. He looked at me like whats wrong with this guy? Its because i asked him for change one time Hey could i get change for a dollar and he mocked my voice as if to say arrrr-rrrrr-rr. Its like that charlie brown show whenever the teacher would talk there would be this weird sound like AWWWA WA AWWA and thats what i kind of sound like to people. This has gotten me so sad because if u cant communicate effectively then life is going to be a pain in the ass. Also i am very quiet so i dont say much and im wondering if im damaging my voice for not using it often. It seems like i have a speech impediment and i need speech therapy. A lot of people have done this wherever i go and im sick and tired of this happening. Well i hope things change soon because if not then i dont know what will happen if i cant talk to people. Let me know if there is anything i can do to help with this problem of mine. Thanks

it can be social phobia and maybe its because of your imagination you can record your voice and then speak to friends asking them about your voice and at last go to therapist,this is not difficult problem cause it has many solutions