Please help my beautiful dog

My name is Karen and I feel so helpless. My poor sweet dog has such skin issue's that he is running in circles in our house crying in pain. I have a carecredit card with a $2000 limit and I have spent it all on my beautiful Houdi. I have done what I could with the limited funds I have but the vet told me he needs to have samples taken of his skin and sent to the lad but it will be very expensive. I can't let my sweet boy suffer but I don't know what else to do but ask for help, I love this dog so very much, my heart aches to see him in such pain. I work hard, I pay my bills, I promise you I do all I can but I have no more to give and I feel helpless. Thank you for reading this and God bless you if you can help.