IV Doxy question regarding burning

I have a PICC for my IV Doxy.  The doc has told me IV Doxy is caustic, I drip very slow, yet after 7 weeks I have developed burning in the middle of my chest (pretty sure at the outflow point of the PICC).  At first it was now and then, now it is every time I drip.  I have dripped even slower, but it seems to be a losing battle as it isn't going away.  I have had the Picc backed up two inches and it got better for three days and now is back full burn.  I had it checked by x ray or some sort of imager and the picc line tip is in the correct spot, it hasn't punctured the vein or anything. 

Does anyone have any information on IV Doxy being caustic and if there is anything I can take to combat the burning, I don't want to ruin my superior vena cava, nor my heart valve.  Is there any danger of permanant damage to my veins?  My PICC nurse is no help, she is the worst nurse ever.  Is there something that adds the buffering capacity of our blood?  Anything that helps repair veins?

I don't want to stop the Doxy just went I am starting to feel good in all other areas of my health.  But this burning just can't go on forever.  If it gets even a littlebit worse I am gonna have to give up.  Any thoughts. 

 

The nurse didn't say anthing at all intelligent, she is rather uninformed. I keep thinking I should switch nursing companies but I am sure that would be too complicated for my insurance to understand and I wouldn't get any coverage.

Then I called the doctor she said some people are just sensitive to the doxy and to drip slower and see if it helps (which it did for about a week). I have had plebitis in my arm veins before and it has always gotten better with time. My only real worry is this is so close to my heart valve I wonder about that. I will ask my doctor next week when I see her, if there can be permanant damage or if there is any sort of buffering agent for my blood. But since she didn't have anything informative to tell me last time I spoke to her, my expectation is that she will just take me off the Doxy, which I really don't want to drop now that it is working. I could find no information at all on the internet about this, which makes me think it is rare or weird.