5 year old with new bilateral ankle clonus

My daughter has exhibited a number of problems over the years but no firm diagnosis yet.

As an infant she had low tone, was left-handed by 4 months of age, showed profound left-sided preference, and was highly delayed with all milestones. She began intensive PT/OT/Speech at age 8 months. When she began to walk she circumducted her right leg, had to be taught all protective reflexes, and had to be taught all movements (i.e., if a toy was placed just out of reach she had to be taught how to move to reach for it). Over time, and with intensive therapy, she learned to walk and talk etc. She is doing very well overall considering her starting point (she can run, dance, play, etc. and is just a little slower and more awkward than her peers. She also tires more quickly).

As she grew older, her tone remained low and is throughout her body (trunks, limbs). Her tongue used to stick out and to the side and she had difficulty swallowing although this improved. She had to be taught to keep her tongue in her mouth. She also had trouble chewing. Her face used to be quite spastic but has relaxed over time and looks very normal. She continues to have low tone and little to no deep tendon reflexes. Mentally she is normal to above-average intelligence; no genetic testing has come back positive; and she has had mixed CK levels from normal to just a bit above normal.

We have had many working diagnoses although none have stuck. They include hypotonia, right-sided hemiparesis, congenital myopathy, global developmental delay. Some have raised the possibility of stroke and global apraxia as well. (FYI: She was breech, moved very little in utero, has hip dysplasia and several other health problems.)

On her recent visit to neuro she exhibited bilateral ankle clonus ("a few beats") for the first time. She had visited a neurologist at least once a year (and often more) since she was about 12 months old. This surprised her dr. who ordered a spinal MRI. However, because she will require general anesthesia for the MRI, we have all decided to wait for 3 months, go in again to see if the clonus is present, and then do a spinal and brain MRI if so because her previous MRI is over three years old.

Other things we've noticed rather recently: she has begun biting her cheeks/tongue unless she is concentrating; she complains of significant muscle pain in her thighs and in her knees in the morning coming downstairs; and about a year ago she began to exhibit greater strength on her RIGHT side and was weaker on her left side. So much so that her therapists wondered what side they were supposed to work on. It's not pronounced but it represents a big change for her.

I am confused about what this might mean. Is it ever normal for a five year old to have intermittent bilateral ankle clonus? Could it be a passing fluke? Based on other postings, where bilateral clonus occurs there are usually  hyperactive reflexes it seems, and this is NOT the case here. Are there conditions that present this way? Is there any reason to be concerned about waiting three months for a follow up exam?

Thank you in advance for any and all suggestions and comments!