Your Google Ad Campaign was off to a great start, you were getting a decent amount of conversions, then all of the sudden it just stopped converting. You're still advertising under the same keywords and you haven't changed bids.
What should you do? Should you try changing the bid strategy?
Testing a different bid strategy can definitely help turn a campaign around and I definitely recommend testing a new bid strategy. Instead of just switching the whole campaign over to a new bid strategy, I recommend creating a Google Ad Experiment.
This will let you basically run an a/b test where X% of your budget is allocated toward your original campaign and X% is allocated toward a new campaign variation, one where you changed the bid strategy.
The reason I recommend doing it this way is you never know when your original campaign will start converting again. You may just not have had statistically significant data and it turns out the original campaign was experiencing a brief slump in performance.
A lot also has to do with how you set up the campaign and if you're making the appropriate adjustments across all dimensions; keywords, ads, demographics, locations, device, time of day and day of the week.