I would throw it away quickly. Making garlic oil is a huge risk for botulism (botulism is a bacteria that thrives in food when there's a lack of oxygen, as is the case with garlic submerged in olive oil).
You CAN make garlic-infused olive oil, but it's best to keep it in the fridge to prevent the botulism from growing. They say that it's difficult to tell when botulism has developed in food, but the air bubbles could very well be caused by the bacteria (anaerobic bacteria can expel CO2).
Botulism CAN cause paralysis and even death, so if you haven't been properly refrigerating your garlic oil, it's not worth the risk. It should be stored at or below 36F/2C. At this temperature, the oil may start to solidify, so it might be necessary to take the oil out a little in advance before using it. It should never be kept out for more than 4 hours at room temperature.