Make sure you have good filter capacitors around the 555. Motors tend to generate a lot of static.

The spec for a 555 is 200ma, but most people limit it at 100ma to insure a long lifetime. The CMOS version runs a lot less than that, though it is a respectable drive for a CMOS chip.

What do you mean by good..? you mean quality or rating of capacitor? also how do i limit the current to 100 mAmps?

 

A good cap might be 50μF @ 25-50V, paralled with a .1μF film or ceramic.To limit 555 out. current to 100 mA , make equivalent load at least 120 Ω. If driving a darlington the resistor would be around 220 Ω.

 

You did not connect a diode parallel to the relay's coil which is very important.

You said you connected the relay coil to the output pin 3 of the 555 and to ground.
But you also said you connected a diode in series with the coil between +Vcc and pin 3 which is not in series.

 

Yep, that diode is important. This was mentioned, and shown. With any inductive load, such as a relay, or a DC motor, you can not eliminate it.