These last months I've been taking guitar more seriously than before, at the moment I'm trying to learn the solo from black sabbath (the song), I can play it, at a slower tempo, but not more than 4 or 5 times without my finger screaming for me to stop, althought thats kinda good, I can't really have any actual progress, I tried some pinky strenghtening exercise, I know this all down to practice and usefull learn time, but I'd like to know if there is any exercise to help me out.

Not sure if right place for this

Thanks in advance
Basically... no. If you want to learn that solo the most effective thing you can do is learn that solo.
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^ agreed, warm up properly! I like to do a chromatic run from 1-12 on each string going up and going down, as well as running through major and minor 7th arpeggios chromatically from G to E and I also practice my 5 positions of the major scale in 3 random keys of my choice before I even think about starting to play properly. Then the only other thing is practice, the more you practice the stronger your fingers will get and the less fatigue you'll feel whilst playing.