Timer and Callback function - how to seperate their data

Hi, I wonder if someone can help me with my problem. So... I have one timer function that is running every 10 ms. In that function I'm sending "?" sign to Arduino board and than read data from Arduino. Also I have slider value change callback. With changing its data Arduino gets another sign - "p", and a value from slider. I don't know why but with changing value of slider all data are send together. It looks like that :

Is there any option for split that data? I tried to add /n or /n/r but when I try to use that /n is being replace with a single dot and data are still together.

[Ameer Hamza]

Can you paste your callback functions, it will help understand, what are you trying to do and what is causing the problem.