I need help plz. Mobile net problem ?

My phone is x2-01 phone. Iam using internet. Tata docomo connection. Does a phone also gets infected by malwares. My net connection has become very slow. For temporary iam using it. Plz tell me how to remove malware or other viruses causing this problem. Is there any websites which gves free anti virus softwares. Iam using it for temporary. So dont want to buy any anti softwares. Is there any free software need help. I already made 2 to 3 times formets but its not so effect. At first times internet was very fast but now its too delaying. Ty.....