priority problem

I have a situation where code runs fine at one setting and not at anther. At issue are two timer routines.
Both are low priority. sThey are timer 2 and timer 3 in a Silabs 040 processor. The PCA is the high priority interrupt. Timer 2 interrupt is used to feed sinewave table to DAC to generate a sine wave. Timer 3 is the system 10 ms heartbeat. if the PCA (which is used to generate pulses) is generating a pules shorter than 8 cycles at 1 mhz, AND it is time for a sound, the sound happens, but the flag to end the sound (which is cleared in the timer 3 routine) never gets cleared, and the ssound runs forever. If you break the code with the debugger, you find that timer 3 has timed out and is requesting an interrupt. IF you change timer 3 priority to high, it will run and the signal will cease, but the pulse train from the PCA will be messed up. I've already addressed that,by making everything else low priority.

NOW: There is one way out of this, and that is to check at the bottom of the timer 2 interrupt, to see if there is a timer 3 interrupt pending, and transfer
control to the timer 3 interrupt. This will work because both interrupts push and pop the same parameters off the stack.

The question is how to do this in C without resorting to an assembly instruction, which results in the compiler emitting assembly code, and you having to assemble it separately. This is not acceptable in my complex build process.

((unsigned car (code*)(void)) Timer_3_vector)();
((void (code*)(void)) Timer_3_vector) ();

results in a CALL which messes up the stack.
I don't have enough space to do this in the stack.

I just need to find a way to do a jump directly to the
timer 3 interrupt routine. setjump/longjump doesn't work in this case.

Goto only works within a subroutine.
AND DON'T tell me this is bad programming practice. I know that full well. This is a well controlled embedded system, so I can get by with something like this, though it makes my skin crawl to think about so doing.

Any ideas?