How often should I ice my back for pain due to overuse, strain, etc. If at all?

3-5x each day. Icing can reduce pain and inflammation. During periods of increased pain, i tell patients to ice for 20 minutes 3-5 times/day. A gel ice pack is often the most convenient and comfortable way to achieve this. Icing more frequently is acceptable but difficult to do for busy individuals.
Acute strain. 10-15 mins at a time, 1-2 xs an hour. Muscle loosens up with ice. Do not forget to do some simple, static stretches also, taking your time please.