I want to find an equation or way to do the followwing in Excel

here is the example

I have a string in one cell and i want for example to count the repetation of word red starting from the right hand side and till the fourth coma (,) only not through over the string

the aim of this is not to count the word i am searching about in the full string i wan to count it in only part of it

here is the example

Blue , red , green , green , red , red , yellow ,

can you help me in that