2 months old sourdough starter smells like glue

My sourdough starter has been pretty active for two months and I decided to give it a chance in the fridge. However, after a week or maybe 6 days later my starter came out with a very strong glue like smell that almost burns my nose. I am very upset about it and I wonder if it is toxic now.

I have a backup starter frozen that is from my starter 1 months old but I do not really want to lose all that activation that I got in that 1 month. 

I would really appreciate any help.