What Causes A Swollen, Tender Tube-like Sensation From My Anus To My Coccyx That Only Appears When I Squat, But Recedes When I Lie Down?

Hi when I squat on the toilet to wipe and wash I can feel some kind of long tube or vain feels swallon it goes from my anus to my coccyx but feels tender on the coccyx side iv never felt it before but iv had it now for 3 weeks I did go to doctor she laid me down and felt around she said she can t feel anything but I notice when I got home if I lay down it receids inword when I squat it pushes out word what can this be not blood in stool