2001 Galant ES 2.4l

I've had a musty smell in my galant for a few weeks now. Here is what I know.

I do not have a cabin air filter
My sunroof does have a leak on the passenger side right at the visor. It does not leak very much but a few drops here and there.
There is discolloration of my headliner to be a little grayer behind the sunroof. That area has never gotten wet before and is not ever wet now.
When the smell started to develop, no carpet or seat was wet anywhere within the car or trunk and has never been since then yet the musty smell continues to develop and get worse.
By sniffing around the car I can not determine where the smell is originating, and it does not seem to be coming from the vents.
I literally just found a hairline crack in my radiator, don't know if this could be attributing to it, however I know what antifreeze smells like and do not smell it while driving.

This has been a great car for me, however now because of this smell I may have sell it as my pregnant fiance can't ride in it, because we have no idea if there are mold spores that could cause an issue, however I continue to drive it daily and my clothes smell musty an hour after getting out of the car...lol
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Any tips? I did some reasearch online and about the only thing I have not checked is the doors to see if water has pooled up in there,but i do not smell anything directly coming from their either. Thanks for your help, if you need any more info, just let me know and I'll check it out. I am mechanically inclined.