i also modulate it with the PWM.
With all modulation, the information you modulate has to be at a much lower frequency than the carrier or modulation frequency.
The simplest way to modulate an IR LED is to change the PWM frequency to 38KHz and write a 50% value to it.
However, to modulate PWM on this you need to work out what frequency of PWM you want. Most modulated IR receivers will only operate a a certain baud rate so you need to look this up and see if it is compatible with what you want. You can then bit bang the PWM by writing alternately 0% and 50% to the modulation either from a timing loop or from an interrupt service routine.
If you use a 555 to provide the modulation you still might have to modify the basic PWM frequency, I believe it defaults to 400Hz and that might be too fast for your receiver.