this provider wrote to me a private message and asked me to check out her profile but I don't see how to get there from her name/alias on the site. how does that work. clicking on her handle only goes to the message, not her profile.

and search by her handle or alias.  Or just search for her by location and look down the list until you find her.  If that doesn't work, I don't know what else to tell you.

I don't see anywhere in the search (even advanced search) where to enter an alias or handle.
I am not about to go through a list of hundred of people to find out who emailed me. there has to be a better away.

go down to the section on Provider's Contact Information.  In the box that says "Provider's name", enter her handle and click search.  If that doesn't work, use her alias.  You could always reply to her and ask for her ID number.  That would make the search much easier.

Why not have a button each time a provider with a profile PMs someone so that the receiver of the PM can check her out easily?

We have it on posts, so why not PM?

I've had some problems in the past finding the sender's profile because often their TER handle for posting and PMs is different from the handle they use on their profile.

frenchy:  Go to the suggestion board and make this a suggestion, if you would.  (Or I'll do it.)