Role of "des"

Question

I don't understand the construction of " j'avais des démangeaisons ".  What is the role of "des"?  It looks like a preposition between an auxiliary verb and a main verb.  Or is "démangeaisons " a noun?  It certainly looks like a verb.  Thanks for any help.

Accepted Answer

Gary, ‘ démangeaison ‘ is a noun. Hence the article -  ‘ des démangeaisons ‘. 
There is also the verb ‘démanger’ - but none of the verb conjugations have the same form as the noun.
https://www.wordreference.com/fren/démangeaison
 https://www.wordreference.com/fren/démanger
 https://www.wordreference.com/conj/frverbs.aspx?v=démanger

Answer

THanks Maarten!  Very concise and clear.