I had similar symptoms before and I googled it just to eased my mind. Usually when you have sex during your period, you have a very low chance of getting pregnant. Since you did it towards the end of your cycle, there is a possibility of pregnancy. Sometimes bloating can be due to hormones. Have your change your daily activities? Sometimes exercise and change in diet could cause bloating too. If clear blue shows up negative, I wouldn't be too worried. Maybe you can try other test kits? If you're still worried and don't trust clear blue, you can try other pregnancy test kits like first response. Here are some links where you can buy test kits. https://www.target.com/s?searchTerm=pregnancy+test
Hope this helps. Best of luck!