You have been fairly investigated. Your symptoms do suggest thyroid abnormalities. But you mentioned that it came out to be normal. Most of the physicians get only TSH for the thyroid evaluation. I would suggest a full work up for thyroid, which includes; T3, T4, free T3, Free T4 with TSH
(if not yet done). The other work up recommended would be parathyroid hormone assay
for your symptoms of dizziness, muscle twitching and anxiety. An ANA panel also would be advised with the anemia work up. Anemia alone can cause all of your symptoms. The most common causes of anemia are;
1) iron deficiency (with or without blood loss),
2) chronic disease/inflammation
3) chronic kidney disease
4) deficiencies of folate or vitamin B-12,
5) diseases of the bone marrow
6) hypothyroidism, hypersplenism, and hemolytic anemia
So investigations entail;
1) Complete blood count (CBC)
2) Peripheral blood film
3) Vitamin B-12
5) Reticulocyte count
7) Thyroid-stimulating hormone
8) Serum creatinine and estimated glomerular filtration rate
9) Serum ferritin
10) Serum iron
11) Total iron-binding capacity.
These work up should be able to point to the diagnosis and accordingly treatment can instituted. Meanwhile Anxiety can be treated by the following measures by yourself;
1) Cognitive-behavioral therapy (CBT) and operant-behavioral therapy (OBT); done by a psychologist.
2) Relaxation training and biofeedback.
4) Acupuncture and acupressure
7) Group sporting activities
8) St. John's wort
10) Valerian root
Muscle fasciculation or muscle twitching is caused by minor muscle contractions in one particular area, or the persistent and uncontrolled twitching of a muscle group in a distribution of a single nerve fiber or filament. Usually they are benign and resolve on their own, but persistent flutter may need following investigations;
1) electromyography (EMG)
2) nerve conduction velocity (NCV)
3) blood electrolytes like calcium, magnesium, potassium, sodium, etc
4) thyroid and parathyroid function tests
5) blood chemistry and complete metabolic profile
The common causes can be;
1) Idiopathic; no cause is ascertained and majority falls in this group.
2) Increased caffeine intake
3) Increased alcohol intake
5) Deficiency in diet and nutrients / minerals
6) Some neurological diseases; uncommon
As we discussed; twitching usually is benign and do not point to any serious issue. Anxiety itself can be responsible for the muscle twitching.
Please feel free for your follow up questions.
I would be happy to assist you further, if you need any more information.