Are you vaping more frequently? That tank can get hot pretty easily, it's small. Are you using the same type of coil resistance? Has your airflow changed? (That can heat a vape up more easily than one might think.) There should be no reason that laying it sideways should change the vape quality.
I would take everything apart, reassemble it and check that all o--rings are seated correctly and the coil (you may need t replace it if it's tasting burnt) and check your airflow settings. You could also go to a local vape shop if you have one near you to get some real world assistance.
It is possible (I would rule everything else out first) that your tank is flooded, as others have said, that will cause spitting, possibly heat, and not a pleasant vape. A gentle blow through the airholes with a napkin to catch drips should take care of most gurgling and spitting IF your coil is seated correctly.
Finally, if nothing you try works, I would consider a warranty/repair if you are still within warranty period.
I will say that personally, I find that setup difficult and probably wouldn't recommend it to a new vaper due to the tank being so small, and it heating up quickly. A lot of folks transitioning to vaping tend to want to chain vape at times, and chain vaping (at any time) is no good in that setup, it just heats too quickly. It might make a good "backup" vape in case anything happened to another setup, but I would respectfully suggest that perhaps a different setup might give you a better vaping experience (whether you figure out the Exceed's foibles or not). I might suggest an aspire zelos setup can get them pretty inexpensively but I think you'd have a better vaping experience. Picos are also well-liked by many MTL users.
Could find prices (in the US or direct from China) on vapecrawler.com.
Best of luck,
Anna