Dexmethylphenidate, sold under the trade names Focalin among others, is a central nervous system (CNS) stimulant used in the treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy. It is in the phenethylamine and piperidine classes of medications. It is the active dextrorotatory enantiomer of methylphenidate.
1 Some allergies cause digestion problems as well. There are also times when you may feel nauseous after every meal. Nausea after meals can also be accompanied with other allergic symptoms, such as, hives or rashes.  Psychological â Sometimes, nausea after eating may also occur due to psychological factors.
Sinus infection causes blockage of flow especially when a person lies down. The blockade is affected by the side to which the person turns also. This could cause a feeling of heaviness in the head on awakening, hence the feeling of unwellness. Sinusitis can be prevented by avoiding the precipitating allergens. Also practice good breathing exercises, humidify your room and do steam inhalations.