I can not say for sure what your problem is. On my Surface Pro 3 I can use My Surface Pro 3 Pen and I can use my Wacom Intuos Pro.
You Did not state Which version of Photoshop your using. If You are using CC 2017 make sure you have you Wacom Preference for Pen Mapping set to use Windows INK and you do not a have a Photoshop preference file that tells Photoshop to use Wintab for Pen support. The file "PSUserConfig.txt" should NOT be in your user ID Photoshop Preferences. Make sure you did not install the WinTab Driver for the Surface Pen. Old version of Photoshop only supported using Pen via WinTab API.
Thanks, I removed the enable wintab from the setting folder and it fixed it. although I'm not sure how this suddenly caused this as it was always there and working fine before I tried installing wacom. Thank you anyway
Wacom Tablet drivers can use Wintab API and they can Use Windows Ink API. Which will be use depends on the Applications you have set up and the Pen Mapping Check Box setting for that Application. Photoshop CC 2015 will use WinTab API if that PSUserConfig.txt file is in you Preferences. It is is not in your preferences it will use Microsoft Windows INK Apl. The Surface Pen Device diver will use Microsoft Windows INK API. However, Microsoft made a WinTab Device diver available for OLD Application that do not support Windows INK APIs.
On my Workstation I have many version of Photoshop installed. CS2 is an old Photoshop Version the only has WinTab API for pen support . So I Configure My Wacon Intuos Pro not to use Windows INK for Photoshop alls other Application Wacom will use Windows INK for All version of Photoshop Wacom will use Wintab API. I add the PSUserConfig.txt file to all the Creative Cloud Photoshop Versions Installed.
On my Surface Pro 3 I do no have any old Photoshop versions installed. So The Surface Pen device Diver uses INK API and the Wacom Driver uses INK API I can use the Surface Pen and I can use the Wacom Pen with Photoshop on my surface.
Why did you choose to use WinTab API with Photoshop you should not have done that. Remove the PSUserConfig.txt file and Check the use Windows INK in the Wacom preferences for Photoshop Pen Mapping. I believe you will then be able to use your Surface Pen and Your Wacon Tablet and Pen with Photoshop CC 2015.