Red line/rash on fingers/arms from doxy?

My 12 year old son who has just been diagnosed (and with a bulls eye) has been on doxy for about a month now.  He has developed a distinct red line with red surrounding dots on the side of his index finger to the tip of his thumb.  Now my husband just called me and said he has it on the backs of his arms. 

Anyone get this from doxy?  I can't find that it is a side effect and don't know whether to take him to pediatrician or not.  Maybe ask pharmacist?  I'm trying to get to the LLMD apt. on Monday.  Ugh this stupid disease!

Yeah I think we figured it out traveler.  My dr. recommended him taking a cat's claw and apparently the rash started since then and got worse last nite after taking it again.  My husband is going to bring him to my office work for me to see show me how bad it is and then I'll decide whether benedryl or doctor but definitely no more cat's claw for him.