At middle of October i left the country for 2 weeks and left my bunny, Misty at home with my boyfriend, When i got back home i noticed a very small spot with no hair on Misty’s neck and a small line a bit red.  Went to vet for a full check up and got a cream to use for 4 days, 2 times a days – name is Dermiel. Vet said skin around looks very healthy so can not be parasites and is possible she did it because of the stress not having me around, No result from the cream but the spot getting bigger, only in baldness so we went back to the vet. After another check the vet doesn’t know what it is, we have an antibiotic to use 10 days, Sulfatrim is  the name of it. On 30 should be last day. If it has no cure?  I dont want to think negative but i dont want to give her medicine for no reason neither i want her sick and me not being able to do nothing  

 She is free in all house besides bathroom and washing room, very spoiled, balanced diet, sleeps in bed with me or on top of the couch. She is active, playful, did not lost weight. She had no fake pregnancy to remove her hair but is visible that thing bothers her….

 I am just wondering if someone had been thru this and can give me an opinion about what could it be so i can lead the vet to find the cure, 

 I will not give her nothing without asking the vet, i am looking for a point where to start searching.

I have attached a pic of this maybe i can get some help.

Thank you very much!