Addition-Subtraction of Numbers Within String
Jelly, 17 15 12 bytes

fØDV€ḂT‘ịƲSḤ


Try it online!

Try test cases.

The program keeps only the digits that follow an odd digit then computes twice the sum.

fØDV€ḂT‘ịƲSḤ   
f                   Remove anything that isn't...
 ØD                 a digit.
   V€               Cast each digit to an integer
         Ʋ          Monad:
     Ḃ              Parity of each digit.
      T             Indices of truthy elements (odd digits).
       ‘            Increment.
        ị           Index into list of digits.
                    Wraps to beginning and if there are no digits this returns 0.
          S         Sum.
           Ḥ        Double.