Is this deep vein thrombosis?

[Yuhyah]

I have Hidradenitis Supperativa so it's not abnormal for me to have lumps and boils on my armpit and groin area. I have had an hs lump that sits on the corner of my armpit connecting my arm to my breast. It has been inflammed on and off for a month or so and I was checking it the other day to see if it had gone down because I was experiencing pain in this area. That's when I noticed a skinny, cord like vein (or what I can only assume is a vein) right next to the hs lump and extending into my shoulder muscle. It is sore to the touch and causes discomfort when I raise my arm. It seems thicker where it is close to the HS lump but feels skinnier with tiny lumps on it the further up I go. I don't have any symptoms like chills or fever. I have had a light cough during the past week or so but otherwise don't feel sick or anything. My most recent doctor visit they did an EKG and some other tests and determined that my heart was perfectly healthy. I don't know what this could be but it's frightening because I cannot feel this vein/structure on my other arm.