Diane, it's most likely just plantar fasciitis and you should just ice and rest the area (elevate!). You don't have to have been doing increased exercise or any "sport" at all, it happens to everyone, so just rest the foot as much as poss.
Only an x-ray can confirm bone or heel spurs, but they too can only be treated with rest, ice and anti-inflammatories. Unless the pain becomes chronic over time, that is, in which case surgery sorts it out, but (depending on the site of the spur) it can leave the foot considerably weakened.