#1
Every time I try to play fast hammer on and pull offs on my bass with my 3rd finger, it just becomes tender and weak! I did this once in February and now its better so I figured trying it now wouldn't be bad. (I tried fast hammer ons on the 3rd to 5th frets of the G string and it immediately felt tender) and this time I tried it on the 7th to 9th fret and it happened again god damnit! I think it's not as bad this time but still annoying. How long will it take this time for the tenderness and weakness to go away!?
#2
Hey Awesome,

It sounds like your finger muscles are still getting used to playing single line/lead type parts. 
I would suggest working with scales or try slower hammer-ons and gradually ramp up the speed.

With exercising your fingers like this, it shouldn't take more than 3 weeks to a month to gain more strength.

It could also be that you're doing the hammer-on/pull off too roughly or in an awkward way.
It's difficult to diagnose well without seeing/hearing it. If you could show a video, it would help us a lot with helping you diagnose the issue.
"Every time you pick up your guitar to play, play as if it's the last time" -Eric Clapton
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