Yes your suspicion is well warranted.
You are likely not metabolizing fats properly.
It is possible that you are low in lipase, bile or
may have a relevant issue with the liver or gallbladder.
Vitamin D, A, E and K are all fat soluble, so you may have more deficiencies, including possibly hormonal deficiencies.
Hormone synthesis is cholesterol - dependant and if your fats are not processed well, you may have an issue not only with ADEK vitamins and hormones, but also with the neurological system and brain function
in the long term.
Vitamin D impacts many organs and bodily systems, as there are vitamin receptors everywhere in the body, however, the digestive system has the most, therefore it's more vulnerable.
You can do a trial of a high quality enzyme formula consisting of Protease, Amylase and Lipase, as well as
some bile salts to see if this helps.
Probiotics would also help, specially in light of your antibiotic treatment, to replenish your healthy gut bacteria.
Multi-strain in the 10s of billions, the type that need refrigeration, would be preferable.
Eventually, you should consider a Functional Medicine
or Naturopathic Doctor to help you rebalance your body
and restore your health.
Cheers,
Niko