Your symptoms are suggestive of vitamin B12 deficiency and along with history of splenic enlargement you might as well have a Pernicious anaemia so you should get this evaluated completely and get started on the treatment as soon as possible.
Tests that may be done include:
Complete blood count (CBC
Lactate dehydrogenase (LDH) level
Vitamin B12 level
Methylmalonic acid (MMA) level
The goal of treatment is to increase your vitamin B12 level.
Treatment may include a shot of vitamin B12 once a month. If you have a very low level of B12, you may need more shots in the beginning. Some people may also need to take vitamin B12 supplements by mouth. vitamin B1 deficiency