Are you exposed to alot of sun daily?

Clear blisters with fluid in them can be a photosensitivity reaction. This can occur if you are using any RX drugs for other reasons.

They can also be fungal, or viral, or allergic.

Viral blisters are activated by the sun.

Do you have rashes anywhere else? How is your general health?

I would try using an oral OTC antihistamine like Benadryl or Zyrtec (not Claritin) and see if it gets better. If it does, then it may be allergic. I see in your profile you are an animal researcher.

Stop the metronidazole for now until you see your doctor.

Possible allergic culprits include feather pillows, or residues of soap and/or fabric softener left on your pillow cases. So double rinse your pillow cases, and don't use fabric softeners for a while.

Allergic eczemas may appear on the face, due to foods as well.
You may have to have testing in the future to see if that is the problem.
Do you have contact with various animals?