The thing you are describing appears to be a thrombus
- a blood clot which had formed over the IV site. Generally the thrombus dissolves by self and doesn't need any medication. Sometimes, it takes 2-3 weeks as well but not generally 6 months. There are two things which are confusing. First why did you receive volumes when it was an anxiety
attack and secondly BP apparatus should never be connected to the hand where the volume is going on. That was a mistake by the nurse or attending doctor. But believe me, a thrombus is never a serious thing and it can be best ignored and will resolve by self. You should be concerned about it only if it is painful or tender or skin above it develops redness
Hope I am able to solve your concerns!