@bigapple33 - Not entirely surprising with RPM @ 55 in a frame as stiff and raw as the PA19. It also doesn't help that RPM's silicone oil coating tends to wear off anywhere between 1 and 5 hours, and at that point any semblance of arm-friendliness is more or less completely removed.
That said, you may not gain enough comfort by replacing one full-bed of poly with another, at any level of softness, but if you'd at least like to try, I'd recommend the following more comfortable alternatives that have similar playability and usually better longevity:
6-10 Sided (some twisted) Shaped:
- Gamma Jet
- Genesis Heptonic
- Gosen G-Spin 3
- MSV Focus Hex Soft (also FH +25, FH +38 if needed), Hepta Twist
- Signum Pro Thunderstorm (10-sided, twisted)
- Tourna Big Hitter Black 7
- Volkl Cyclone Tour 16 (don't bother with 17 or 18, they pale in comparison)
- Yonex Poly Tour Rev
- YTEX Quadro-Twist, Square-X, Octo-Twist
Round:
- Gosen G-Tour 3
- IsoSpeed Cream
- MSV Swift
- Tier One Ghost Wire
- Yonex Poly Tour Pro
- YTEX ProTour
Optionally, you could do a P/P hybrid, of one of the shaped mains from the above list, with one of the round crosses.
As you try out strings, first try dropping tension in that gauge your used to, then reduce gauge, then decrement tension again.
If none of the above works, I would look at hybriding natural gut or durable multi mains (Multifeel, Quasi Gut Armor, etc.) with a slick but gentle poly cross like Ghost Wire, Swift or Cream.
If that fails, too, then hybrid gut mains with Multifeel crosses (ie. arguable the slickest non-poly synthetic out there), and if that fails, full-bed natural gut.
Beyond that, you could add weight to the frame to try and increase comfort, but otherwise, new frame altogether.